JP2002288900A - Floating optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a floating optical head that improves heat radiation efficiency of the magnetic coil producing the recording/reproducing magnetic field on a magneto-optical recording disk. SOLUTION: The protective film 12 is made thin except a projection 122 at the center of a magnetic coil 13. Accordingly, the copper wire of the magnetic coil 13 is brought closer to the open air resulting in improved heat radiation efficiency. The coil 13 consists of several layers and the layer has the more turns the closer the open air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flying optical head, and more particularly, to a flying optical head having a coil for applying a magnetic field for recording and reproduction to a magneto-optical disk.

[0002]

2. Description of the Related Art In a recording / reproducing apparatus for a magneto-optical disk,
An optical head that irradiates a magneto-optical disk with a laser beam and applies a magnetic field is used. This optical head is provided with a magnetic coil for generating a magnetic field on the optical axis of the laser beam.

At present, in a recording / reproducing apparatus which is actually commercialized, an optical head is mounted on a sled mechanism so as to be movable in a radial direction of the magneto-optical disk while maintaining a constant interval from the transparent substrate surface of the magneto-optical disk. Has become.

On the other hand, recently, a flying optical head (also called a slider) has been developed which flies over a magneto-optical disk as the magneto-optical disk rotates. Since this flying type optical head flies at a small interval from the surface of the recording film of the magneto-optical disk, it is particularly suitable for recording and reproducing on a magneto-optical disk having a high recording density.

Japanese Patent Laid-Open Publication No. 2000-215427 discloses such a floating type optical head, for example, in which a protective film on a floating surface facing a magneto-optical disk is patterned to form two rail portions on both sides of the floating surface. A floating optical head is described.

Japanese Patent Application Laid-Open No. 2000-229555 discloses a flying optical head in which a protective film on a flying surface is patterned to form a U-shaped rail.

Further, T. Irita et al. "A Proposal of M
icromachined Optical Flying Headwith Micro Solid I
mmersion Lens "ISOM '98 Technical Digest (Oct. 1998
20-22) In pp.152-153, a floating type with a protective film on the air bearing surface is patterned to form two rails on both sides of the air bearing surface and one rail supporting the micro solid immersion lens at the center. An optical head is described.

[0008]

However, none of the above-mentioned floating optical heads takes measures against heat generation of the magnetic coil. That is, since the magnetic coil generates Joule heat in accordance with its resistance and inductance, its allowable current has a certain limit. If the allowable current is small, the magnetic coil cannot generate a strong magnetic field, and the recording / reproducing characteristics cannot be improved.

In the floating type optical head described in the above two publications, the protection film on the air bearing surface is patterned to make the laser beam transmitting portion convex, but since no magnetic coil is described, The magnitude relationship between the size of the convex portion and the size of the magnetic coil is unknown.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a flying optical head having a high efficiency of radiating Joule heat generated from a coil.

[0011]

A flying optical head according to the present invention comprises a substrate, a plurality of layers of coils formed on the substrate, and a protective film formed on the substrate so as to cover the coils. The floating type optical head is characterized in that the thickness of the peripheral portion of the central portion of the protective film is smaller than that of the central portion of the coil.

The flying optical head flies over the magneto-optical disk as the magneto-optical disk rotates, and applies a magnetic field from the coil to the magneto-optical disk. At this time, Joule heat is generated from the coil, but the thickness of the protective film at the peripheral portion of the central portion is smaller than the thickness of the protective film at the central portion of the coil, more specifically, the convex shape at the central portion of the coil. Since the size of the protective film is smaller than the size of the coil, heat generated from the coil is easily conducted to the outside air, and as a result, heat radiation efficiency is increased.

[0013] Preferably, the protective film has rail portions formed on both sides of the coil. In this case, since air flows into the upper part of the coil along the rail, the heat radiation efficiency is further improved.

Preferably, the number of windings of a coil in a layer far from the substrate is larger than the number of windings of a coil in a layer near the substrate.
In this case, most of the Joule heat is generated from a coil having a large number of windings. However, since this coil is located in a layer far from the substrate, that is, in a position close to the outside air, the heat radiation efficiency is further improved.

Preferably, the semiconductor device further includes a metal film formed on a peripheral portion of the protective film. In general, since the thermal conductivity of metal is high, in this case, heat generated from the coil is easily transmitted to the outside air through the metal film, and as a result, the heat radiation efficiency is further increased.

In one embodiment of the present invention, the protective film is made of an optically transparent material such as alumina, and the metal film is made of A
u, Cu, Al, Cr, Ti or Ta, or an alloy thereof.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

FIG. 1 is a perspective view showing an external configuration of a flying optical head according to an embodiment of the present invention. FIG. 2 shows FIG.
It is sectional drawing of the II-II line in a middle.

Referring to FIGS. 1 and 2, this flying optical head 10 includes a substrate 11, a protection film 12 formed on the main surface of the substrate 11, and a magnetic coil embedded in the protection film 12. 13 and a plano-convex objective lens 14 attached to the main surface on the opposite side of the substrate 11.

The substrate 11 is made of an optically transparent material such as glass. As a glass, for example, a refractive index of 1.5
1 BK-7 is used. 589nm instead of glass
Alumina (aluminum oxide Al ₂ O ₃ ) having a refractive index of 1.76 at the above wavelength may be used.

The protective film 12 forms an air bearing surface (generally called an “air bearing surface (ABS)”) facing the magneto-optical disk 15. The protective film 12 includes a sheet-like base portion 121 formed on the main surface of the substrate 11 and the magnetic coil 1.
3 and a protruding portion 122 formed directly above the center portion
And a bar-shaped rail portion 1 formed on both sides of the protrusion 122
23a and 123b. The protective film 12 is made of an optically transparent hard material such as alumina. The thickness of the protective film 12 is 8 to 10 μm in total, and
21 has a thickness of 5 to 8 μm. The rail portions 123a and 123b are provided facing each other and apart from each other.
The rail portions 123a and 123b are
5 extends along the running direction of the floating type optical head 10. A taper 123 is provided in front of the rail portions 123a and 123b in the traveling direction so that the floating type optical head 10 smoothly floats with the rotation of the magneto-optical disk 15.
a1 and 123b1 are formed respectively. The base portion 121 includes a first layer 12 formed on a main surface of the substrate 11.
11 and a second layer 12 formed on the first layer 1211
It consists of 12.

The magnetic coil 13 has a laminated structure. More specifically, the magnetic coil 13 includes a spiral coil 131 formed in the first layer 1211 and a second layer 1.
And a spiral coil 132 formed in the inside 212. Here, the number of turns of the coil 132 is larger than the number of turns of the coil 131. The objective lens 14 is arranged so that its optical axis coincides with the central axis of the magnetic coil 13. The protrusion 122 of the protective film 12 is also arranged such that its center coincides with the center axis of the magnetic coil 13. Therefore, the laser beam LB is refracted by the objective lens 14, passes through the substrate 11, passes through the center of the magnetic coil 13, and is focused on the film surface of the magneto-optical disk 15.

Next, a method of manufacturing the flying optical head 10 will be described. 3 to 5 show the floating type optical head 10.
FIGS. 6 to 10 are cross-sectional views showing the manufacturing process. In particular, FIG. 7 shows VII in FIG.
8 is a cross-sectional view taken along the line VIII-VIII in FIG. 4, and FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG.

First, as shown in FIG. 6, the main surface of the substrate 11 is plated with copper to form a spirally patterned coil 131.

Subsequently, as shown in FIGS. 3 and 7, a first layer 1211 of the protective film 12 is formed on the main surface of the substrate 11 so as to cover the coil 131, and copper plating is further performed thereon. A spirally patterned coil 132 is formed. At this time, a lead wire (not shown) for supplying a current to the coil 131 and the coil 132 is also formed. Here, the quality of the resistance and inductance of the magnetic coil 13 is inspected.

Subsequently, as shown in FIG. 4 and FIG.
Over the coil 132 so as to cover the coil 132
Of the second layer 1212 is formed. Here, the first layer 12
CMP so that the entire thickness of the protective film 12 composed of the second layer 11 and the second layer 1212 becomes uniform and the surface becomes flat.
(Chemical Mechanical Polishing)
Polish the surface.

Subsequently, as shown in FIG. 5, the protective film 12 is cut into strip-shaped bars, and the protective film 12 is patterned by ion beam etching or mechanical polishing so that the air bearing surface has a predetermined shape. As a result, the protrusion 12 as shown in FIG.
2 and rail portions 123a and 123b are formed.

Finally, the semi-finished product shown in FIGS. 5 and 9 is cut into chips. Thereby, a chip as shown in FIG. 10 is obtained. Here, the quality of the processing of the rails 123a, 123b and the protrusion 122 is inspected, and after selecting good products, the objective lens 14 is attached to the substrate 11 on the side opposite to the coil 13 side.

When the flying type optical head 10 having the above-described configuration is used, air flows into the air bearing surface with the rotation of the magneto-optical disk 15, but protection just above the magnetic coil 13 (around the projection 122). Since the film 12 is thin, Joule heat generated from the magnetic coil 13 is easily conducted to the inflowing air, and the heat radiation efficiency is increased. The projection 122 remains in the center of the magnetic coil 13 and the upper surface of the projection 122 is finely polished by CMP, so that the optical path length of the laser beam does not deviate from the design value.

In the magnetic coil 13, the number of windings of the coil 132 of the second layer 1212 is changed to the first layer 1211.
Is larger than the number of windings of the coil 131. Therefore, although the Joule heat generated from the coil 132 is large, the coil 132 is closer to the outside air, so that the heat radiation efficiency is further improved. Further, since the diameter of the laser beam LB becomes smaller as it approaches the magneto-optical disk 15, even if the number of windings of the coil 132 closer to the magneto-optical disk 15 is increased, the optical path of the laser beam LB is not hindered.

As described above, according to the present invention, since the heat radiation efficiency of the magnetic coil 13 is high, the allowable current of the magnetic coil 13 can be increased, and the generated recording / reproducing magnetic field can be increased. As a result, the recording / reproducing characteristics can be improved. On the other hand, since the heat radiation efficiency of the magnetic coil 13 is high, the winding density of the magnetic coil 13 can be increased and the magnetic field generation efficiency can be increased. As a result, the current required to generate the same recording / reproducing magnetic field as the conventional one can be reduced, and the power consumption can be reduced. Therefore, the flying optical head 10 is particularly suitable for a small portable device that has been in great demand in recent years.

The embodiment of the present invention has been described above.
The present invention is not limited to the above-described embodiment, but can be implemented in other forms.

For example, as shown in FIG.
Protective film 12 excluding 23a, 123b and protrusion 122
A metal film 21 may be formed thereon. Such a metal film 2
For example, after forming a metal film on the entire air bearing surface of the protective film 12, the rail portion 123 is formed.
What is necessary is just to remove the metal film on a, 123b and the protrusion 122 by lift-off. If such a metal film 21 is formed, the thermal conductivity of the air bearing surface increases, and the heat radiation efficiency of the magnetic coil 13 further increases. Metal film 12
Is, for example, Au, Cu, Al, Cr, Ti or T
a, or an alloy thereof.

The substrate 1 according to the above-described embodiment is
1 is made of an optically transparent material such as glass or alumina, but may be made of an optically opaque material such as ceramic. In this case, a through hole is formed in the substrate to allow the laser beam to pass.

The embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external configuration of a flying optical head according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a perspective view showing one step in a method of manufacturing the flying optical head shown in FIG.

FIG. 4 is a perspective view showing a step subsequent to FIG.

FIG. 5 is a perspective view showing a step subsequent to FIG. 4;

FIG. 6 is a sectional view showing a step before FIG. 3;

FIG. 7 is a sectional view taken along line VII-VII in FIG. 3;

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a sectional view taken along line IX-IX in FIG. 5;

FIG. 10 is a sectional view showing a step subsequent to FIGS. 5 and 9;

FIG. 11 is a sectional view showing a configuration of a flying optical head according to another embodiment of the present invention.

[Explanation of symbols]

10 floating optical head, 11 substrate, 12 protective film, 1
3 magnetic coil, 14 objective lens, 122 protrusion, 1
23a, 123b Rail part, 131, 132 coil, 1211 first layer, 1212 second layer, 21
Metal film.

Claims (7)

[Claims] A floating optical head comprising: a substrate; a plurality of layers of coils formed on the substrate; and a protective film formed on the substrate so as to cover the coils. A floating optical head, wherein a thickness of a peripheral portion of the center portion is smaller than a thickness of a central portion of the coil. 2. The floating optical head according to claim 1, wherein the protection film has rail portions formed on both sides of the coil. 3. The floating type according to claim 1, wherein the number of windings of a coil farther from the substrate is larger than the number of windings of a coil closer to the substrate. Light head. 4. The apparatus according to claim 1, wherein the protective film is made of an optically transparent material.
Item 6. A floating optical head according to item 1. 5. The floating optical head according to claim 1, wherein said protective film is made of alumina. 6. The floating optical head according to claim 1, further comprising a metal film formed on a peripheral portion of the protective film. 7. The metal film is made of Au, Cu, Al, C
7. The flying optical head according to claim 6, comprising at least one selected from the group consisting of r, Ti and Ta.